They also aren't making close to $20/view on a video, which is enough for even one viewer to pay for having that video reviewed by hand for infringement. Moreover, youtube has setup many systems in place to detect infringing materials. With the charges that Udemy has per copy, they should be paying people to review every video.. or have a $50 upload fee that covers that manual review process. That would kill a lot of the problem.

Youtube actually have quite a civilised policy on pirated content. They do make money on the ads but if you go to them and prove you are the copyright holder they divert the ad payout on pirated stuff to you rather than the poster. I've got a friend making quite a lot of money by having asserted legal copyright on some much pirated content. Udemy could perhaps offer to do something similar?

I agree, wrt youtube's current policies. I'm just stating that given the pricing model Udemy has in place, that a manual review process on every video would not be unreasonable, as compared to say youtube.